1. Field of the Invention
The present invention relates to an image forming apparatus.
2. Description of the Related Art
As image forming apparatuses, there have been known liquid-droplet-ejection-printing-type image forming apparatuses that have a liquid droplet ejection head, in which multiple nozzles are arranged, so as to form an image (including characters) on a sheet of paper by conveying the sheet of paper (recording medium) to the liquid droplet ejection head and ejecting droplets of liquids, such as inks, from nozzles onto the sheet of paper.
In such liquid-droplet-ejecting-printing-type image forming apparatuses, the sheet of paper is conveyed in a state where the sheet is close to the nozzle surface of the liquid droplet ejection head. Hence, in accordance with posture of a sheet of paper, the sheet of paper may collide with nozzles. For this reason, there may be defects such as an ejection failure caused by attachment of dirt onto the sheet of paper, conversely occurrence of scratches on the nozzle surface, clogging of paper powder in the nozzles, or the like.
Accordingly, JP2010-76872A proposes an image forming apparatus that transmits a beam along the conveying surface for conveying a sheet of paper, compares the received light amount of the beam detected by the light receiving sensor and the reference received light amount, determines that the sheet of paper is floated if the received light amount is less than the reference received light amount, and avoids collision between the sheet of paper and the nozzle surface.